使程序有发现设备的能力和操作设备.它主要是用过一系列的回调函数来实现这些功能.像设置高频头的频率,帧频,视频压缩格式和图像像参数等等（在我写的FM驱动中就主要是设置频率，设置音量等）-The program has the ability to discover devices and operating equipment. It is primarily a series of callback functions used to achieve these functions. Tuner like to set the frequency, frame rate, video compression and image as parameters and so on (in my FM write driver is set on the main frequency, set the volume, etc.)